Snap-action mechanism



Reissued May 2s, 1929.

UNITED STATES `PATENT OFFICE.

GEORGE A. KNAAK, OF MILWAUKEE, WISCONSIN, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 PENN ELECTRIC SWITCH CO., 0F DES MOINES, IOWA, A CORPORATION OF IOWA.

SNAP-ACTION MECHANISM.

Original No. 1,618,963, dated February 22, 1927, Serial No. 288,849, filed April 9, 1919. Application for reissue filed February 18,

This inventipn relates to snap action mechanisms and the object of the invention is to improve the construction of snap action mechanisms in the manner to be hereinafter described and claimed.

IReferring to the drawings which accompany this .specification and form a part hereof, which drawings illustrate an embodiment of this invention, and on which draw- A ings the -same reference characters are used to designate the same parts wherever they may appear in each of the several views:

Figure 1 is an elevation of a snapmeehanism showing the parts in the relative posivtions which they occupy in one positive, predetermined position of the actuated member. Figure 2 ishan elevation of the same mechanism showing the parts in the relative positions which they occupy in an impositive position of the actuated member when the parts are in positions for instantaneous change from one positive, predetermined position to another positive, predetermined position of the actuated member. Figure 3 is anl elevation of the same mechanism showing the parts in the relative positions which they occupy when the actuated member has been snapped'to another positive, predetermined position.`

In all snap action mechanisms with which I am familiar, prior to my invention, there is a dwell in the] operation of the mechanism while parts lare moving to change the actuated member from one positive, predetermined poi v r sition to another positive, predetermined position. This dwell rendered the operation of the mechanism impositive and uncertainand Was generally objectionable and in some mechanisms was positively injurious. The object 4of this invention is to eliminatethe dwell or dwell oint of such rior mechanisms.

For the 4sake of simplicity of illustration and description I have illustrated this invention as applied to aform of snap action,` electric switch, and shall describe it as applied to such use Without, however, intending by such illustration and description to limit my invention touse with an electric switch.

Referring tothe drawings, the reference numeral 1 designates a casing within which bell-crank lever 2 is pivoted upon a pivot 1929. Serial No. 340,936.

crank lever 2 upon its pivot 3 in the opposite direction when the push of the plunger 4 decreases, in a manner which will be readily understood.

It may be assumed that the plunger 4 is responsive toany changeable condition whatever, as for example, the pressure of a Huid or a temperature' condition. Movements of sufficient magnitude of the bell-crank lever .2 lwill ,move the actuated'member 6 from one positive, predetermined position to another positive, predetermined position. The actuated member 6 is pivoted upon a pivot 7 and v has oppositely inclined faces 8 and 9 at one end which are shown by the drawings as meeting in a point 10.y A pin 11 projects intoi'an vaperture 12 in the actuated member 6 and serves as astop to limit the extent of movement of the actuated member 6 about its pivot 7 in either direction. A spring-bridge switch member 13 is illustrated as connected with the actuated member 6 so as to be pressed against electric contacts 14 and15 to establish an electric circuit between' the wires 16 and 17 when the actuated member 6 is in one positive, predetermined position and so as to be removed from the electr-ic contacts 14 and 15, to break the circuit, when the actuated member (i is in another positive, predetermined position.

A second bell-crankxlever 1.8 or actuating member is pivoted to the bell-crank lever by a pivot 19 and is illustrated by the drawings as composed of a back 2O and sides 21 and 22. This construction is illustrated as a simple .construction which may-be adopted for conv venience in manufacturing.

An arm 23 is pivoted to the second'belljV crank lever 18 and is provided with a part, which is illustrated as an anti-friction, roller 24, adapted to bear against the end of the actuated member 6. f A stop pinV 25 is secured to the second bell-crank lever 18 and passes through an aperture 26 in the bell-crank lever 2 to limit the amplitudeof movement of the second bell-crank lever 18 with respect to the bell-crank lever 2. A spring 27 is connected with the'arm 23 and with the second bellis a common actuating spring 27 against the inclined face 8 of the actuated member 6 and member 6 in a positive, predetermined posi-v tion with the switch member 13 pressed against the contacts 14 and 15. If now the plunger 4 is moved to the right, the bellcrank lever 2 is turned about its pivot 3 a stretching the spring 5 and the arm 23 is moved down, the antlfriction roller 24 moving down the inclined face 8 and swinging the upper end of the arm 23 to the right and stretching the spring 27. While this motion continues the actuated member 6 is held in a posit-ive, predetermined position with the against the 'contacts 14 and 15 because the right hand end of the actuated member 6 is being pressed down and, as the arm 23 is 'doing this pressing, the stop pin 25 will be in its uppermost position in the aperture 26.

The instant the antifriction roller 24 runs onto the point 10 of the actuated member 6,

Vthe actuated member 6 is in an impositiva position or condition and, if the movement of the plunger 4 were very slow as is frequently the case, the mechanism would not be under control. The point 10 represents a position of inaction, uncertainty or dwell in the positive action of the mechanism, but my invention4 eliminates the inaction, `uncertainty or dwell of the prior mechanism aswill now be p explained. Vhen the antifriction roller 24 has rolled olf the inclined face`8 onto thepoint 10, there is no resistance to the downward movement of the arm 23. The tension of the spring 27 can, therefore, swing the second bell-crank lever 18 on its pivot 19 and pull the arm23 down. The extent of movement is limited by the stop pin 25 in the aperture 26. The action is instantaneous no matter how slow may he the movement of the plunger 4Vand the bell-crank lever 2. As soon as the antifriction roller 24 passes belowthe point 10, the tension of the spring 27 pulls the arm 23 to the left and the antifriction roller 24 presses against the inclined face 9 of the actuatedf member pivot 7 into another positive, predetermined posit-ion in which the switch member 13 is removed from the contacts 14 and 15, as clearly shown by Figure3 of the drawings. When the spring 5 causes movement of the bellcrank lever 2 in the opposite direction, the mechanism will act in the` reverse manner as 6 and swings it about its `will-be readily understood.

The inclined faces 8 and 9 need not meet in a point as it is only necessary that the arm 23 can be moved independently of the bellcrank lever 2 when it has cleared an inclined 23 and the second bellface, but this specific construction has been chosen for illustration because it clearly eX- empliiies the invention and its advantages.

'lt will readily be seen that the inclined faces Sand 9 and the roller 24 provide interengaging elements, one of which has inclined having an engaging part, whereby the spring 27 holds the interin forcible contact, such forcible contact being equally as well applied on either side of the apex or point 10 between the two inclined faces 8 and 9.-

It will further be seen lostfmotion connection'in one of the interengaging elements that as a result thereof, one element willimove relative to the other across the point 10 so that the elements will interengage bycontacting forcibly either with the inclined face' 8 or the inclined face 9. It is the lost-motion connection of one of the ele- 'ments that enables the actuated member to moving the lever in opposite directions, an

arm connected with said lever and provided with a part adapted to bear against the inclined faces atthe end of the actuatedmember, a spring to press said arm against the -actnated member, and means to move said arm independently with respect to said lever.

2. The combination witha pivoted actuated member provided with oppositely inclined faces, of a bell-crank lever, means to rock said lever in one direction, aspring to rock said lever in the opposite direction, a second bell-crank lever pivoted to the first mentioned bell-crank lever, an arm pivoted to the second bell-crank lever and having a part adapted to bear against the inclined faces on the actuated member, and a spring to actuate said arm and said second bell-crank lever. 'y

3. The combination with a pivoted actuated member provided with' oppositely inclined faces, .of a lever, means to move said lever in one direction, a spring to move said lever in the opposite direction. a bell-crank lever pivoted to said lever and having a limited movement with respect thereto, an arm pivoted to f' said bell-crank lever and having a part adapted to bear against the inclined faces on' the actuated membergand a spring connected With said arm and with said bellcrank lever to hold the arm in contact with an inclined face on the actuated member.

4. The combination with a pivoted actuated member provided with oppositely7 inclined faces at one end, of a lever, means for moving.the lever in opposite directions, an arm connected with said lever and provided with a part adapted to bear against the inthat by providing a v vlever in opposite directions,

clined faces at the end of the actuatedv memmember, a spring for normally holding said' arm and actuated member in contact and said lever having an aperture therein, said arm having a part passing looselyvthrough said aperture to provide for limited movement of the arm independently of and relative to said lever. t

6. The combination With a pivoted actu ated member provided with oppositely inclined faces at one end, of a lever, means for moving the lever in opposite directions, an arm connected with said lever and provided with a part adapted to bear against the inclined faces at the end ofthe actuated member, a spring for normally holding said arm and actuated member in contact, and a lostmotion connection between said arm and lever.

7. The combination with a pivoted actuated member, of a lever, means for moving the an actuating member connected with said lever, said actuated and actuating members being provided with interengaging elements, including oppositely inclined faces on one of said members and an arm on the other lmember having an engaging part'to bear against said inclined faces, anda spring for normally effecting a forcible contact` between said engaging part and the inclined faces, said arm being provided with a lost-motion connection permitting a slight independent movement thereof.

8. The combination with a pivoted act-uated member, of a lever, means for moving thelever in opposite directions, an actuating member connected with said lever, said actuated and actuating members being provided with interengaging elements, including oppositely inclined faces on one of said members and an arm pivotally mounted on the other member having an anti-friction roller to bear against said inclined faces', and a spring for normally effecting a forcible contact between said engaging part and Vthe in clined faces, said arm being provided with a lost-motion connection permitting a slight independent movement thereof.

9. The combination with a pivoted actuated member, of a lever, means for moving the lever in opposit'e directions, an actuating member connected with saidlever, said actuated and actuating members being provided with interengaging elements, including op-v positely inclined faces on one of said members and an arm pivotally mounted on the other member having an anti-friction roller to bear against said inclined faces ,and a spring for normally effecting a forcible contact between said engaging part and the inclined faces, sai-d arm being provided with a 10st-motion connection, whereby said actuated member is -held in one of two positive, predetermined positions until movement of said leverin either direction causes said roller to pass from one inc-lined face to the other, whereupon thetension of said spring will cause said actuated member to pass at once to its other positive predetermined position.

10. The combination with a pivoted actu- -ated member, of a lever, means for moving the lever in opposite directions, an actuating member connected with said lever, said actuated member and actuating member being provided with interengaging elements, including oppositely inclined faces on one of said members and an arm connected with the other of said members, provided with a part adapted to bear against said inclined faces, a spring to press said part against the inclined faces, whereby movement of said lever in either directionefects relative movement of said part and the inclined faces of said member, and means to move said arm and through said arm theactuated member, independently of the movement imparted by said lever.

11. The combination with apivoted actuatedmember provided with oppositely inclined faces at one end, of'a lever, means for Vmoving the lever in opposite directions, an

arm connected with said lever and provided with a part adapted to bear against the inclined faces at the end of the actuated member, a spring for normally holding said arm and actuated member in contact, and alost-y motion connection for permitting snap movement .of said actuated member under the inluence of said spring independently of the movement imparted thereto by the lever.v

12. The combination with a pivoted actuated member provided with oppositely in-f clined faces at one end, of -a lever, means for moving the lever in opposite directions, an arm connected with said lever and provided with a part adapted to bear against the inclined faces at the end of the actuated member, a spring topress said arm against the actuated member, sai-d arm being provided with a slot-and-pin mounting whereby it 1n a v be moved independently with respectV to said lever.

13. The combination with a pivotally mounted actuated member, of a lever, means actuated and actuating members being providedwith interengaging elements, incluiding oppositely inclined faces on one of said members and an' anti-friction roller to bear lli against said inclined faces, and a spring for normally effecting a forcible contact between said engaging part and the inclined faces, one of said members being provided with a '5 lost-motion mounting whereby said actuated member is held in one of two positive, predetermined posltlons until movement oi said lever in either direction causes said roller to pass from one inclined face to the other,

whereupon the tension of cause said actuated member to pass at once to its other lpositive kpredetermined position.` Des Moines, Iowa. February 14. 1929.

GEORGE A. KNAAK.

said spring will 104 

